Depressive Symptoms in Early Pregnancy Linked to Lower Breast Milk DHA Levels

Some women develop depressive symptoms during or after childbirth, but it is unclear why some women do and others do not. A history of depressive illness and difficult socioeconomic conditions increase the risk of developing this condition, but other factors, including nutrition may contribute as well. Several studies have examined whether a woman’s long-chain fatty acid status is associated with the odds of developing perinatal depressive symptoms. There is good reason to think that having too little of the long-chain omega-3s found in fish and shellfish in tissues may contribute to the risk. These fatty acids are necessary components of the brain and contribute to its structure and function. Low omega-3 status has often been associated with a higher risk of depressive illness unrelated to pregnancy. In Western countries, fish intake is generally low, especially among women. Unless a woman takes fish oil or omega-3 fatty acid supplements, she is likely to have low concentrations of these fatty acids in her blood and tissues. Having a low seafood omega-3 status may limit the amount of these fatty acids, especially DHA, she has available to pass on to the developing fetus and supply in her breast milk. Because no one had actually measured the breast milk omega-3 content from women with depressive symptoms, researchers at the University of North Carolina, U.S., examined this question. The researchers recruited pregnant women at less than 20 weeks’ gestation and followed them through their pregnancy and the first 4 months after delivery. They assessed the women twice during pregnancy for symptoms of depressive illness and measured the fatty acids in their breast milk in the 4th month after delivery. The assessment of dietary omega-3 consumption indicated that these women consumed less than one-third of the recommended intake of omega-3s during pregnancy. At less than 20 weeks’ gestation, 12% of the women had symptoms of depressive illness and this proportion increased to 16% by weeks 24 to 29. These estimates are at the higher end of some, but not all, estimates of the prevalence of depressive symptoms during pregnancy. Women with fewer years of education, lower income, younger age and who smoked were more likely to have symptoms of depressive illness. The low consumption of omega-3s was also reflected in the low concentrations of DHA in breast milk. Women with more than 16 years of education had higher breast milk DHA, but the level was still 25% below the worldwide average. For less educated mothers, the breast milk DHA level was less than half the worldwide average. The investigators also observed a significant association between the depressive symptoms in women at less than 20 weeks’ gestation and low breast milk DHA content. While this association does not establish that low DHA causes depressive illness, it suggests a link. It also raises a red flag about the mother’s and her infant’s nutrition. With these low intakes and low breast milk DHA concentrations, both mother and infant have suboptimal nutrition. This situation can be readily improved if the mothers include fish in their diet regularly. Greater fish or fish oil consumption by these mothers may not improve the mothers’ symptoms of depressive illness, but the fatty acids they contain will help build better brains for both mother and child.